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Scientific news from Division 6

News 2022

Modern image processing and reconstruction procedures require image quality metrics that work without the need for a linear, shift‑invariant system. In collaboration with external partners, Working Group 6.24 (Medical Imaging) is currently developing alternatives to established quality benchmarks. The first building block in this endeavor is now ready for presentation: a new non‑parametric...

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Versuchsaufbau

A detector setup is currently being developed for the investigation of neutron‑induced reactions on carbon at energies above 100 MeV. The objective is the determination of the energy and angular distribution of the emitted light charged particles as a function of the neutron energy, to produce data of interest for medical applications. The prototype setup was tested...

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The response of a germanium detector was determined for photon energies up to 420 keV. Subsequently, the photon spectra of several of the Division’s X‑ray facilities were characterized with this detector.

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In the last few years, a new radiotherapy modality, called FLASH radiotherapy, has been investigated and is showing advantage over conventional treatment modalities. To test the FLASH modality and quantify its advantage over conventional treatments, new dose measurement techniques and codes of practice have to be studied and elaborated. For this purpose, the EU funded EMPIR project, UHDPulse, has...

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Ethanol is being increasingly generated using renewable energy sources in order to replace fossil fuels. This process, however, also causes larger quantities of ethanol to be released into the atmosphere. There, it forms radicals and then interacts with primary and secondary cosmic radiation, which damages the ozone layer. To better understand these processes, the differential elastic electron...

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Due to the COVID‑19 pandemic, the comparison measurement could not be carried out as usual with a personally monitored evaluation on site at the dosimetry services. As an interim solution, PTB sent the dosimeter probes to the dosimetry services by post after irradiation. The dosimetry services were to evaluate the probes by an appointed date, document the evaluation by means of video or photos and...

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The EPM project known as 21GRD02 BIOSPHERE, which started on 1 October 2022 and is being coordinated by PTB, will for the first time develop metrological methods to investigate the mutual effects of cosmic radiation and biologically active UV radiation on the Earth’s biosphere. This project supports <acronym title="European...

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Bonner sphere spectrometers (BSS) are widely used for neutron spectrometry at reactors, accelerators, and medical facilities. The analysis of the data requires unfolding methods, which need to be used properly to obtain reliable results. The PTB working group Neutron Spectrometry, together with the Paul Scherrer Institute (PSI), organized a four-day course on...

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The compact design and functionality of the highly sensitive and precise electronic measuring systems required for this purpose have been fundamentally improved for measurements with ionization chamber transfer standards in the field of radiation protection. Due to the enhancements, the electronic measuring systems can now also be used in narrow locations, for example, inside radiation protection...

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The focus of the first meeting of the steering committee of the European Metrology Network for Radiation Protection (EMN RP) in February 2022 was the creation of the Strategic Agenda (SA) on the goal, vision and mission of the EMN and the development of a Strategic Research Agenda (SRA) through identification and prioritization of metrological...

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Dosimetric measurements in modern radiotherapy with complex therapeutic techniques (e.g., stereotactic radiation therapy) require extensive corrections of the measurement signal, for example, to take disturbing effects due to the presence of a measuring detector into account. Determining these corrections often requires a complex mathematical process. Correcting the so‑called volume averaging...

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For decades, the irradiation facility for beta radiation, the Beta Secondary Standard BSS 2 developed at PTB, has been in worldwide use to irradiate dosemeters, detectors and other devices with calibrated beta sources. In this work two energy-reduced radiation fields based on the 90Sr/90Y source are described. The fields with beta mean energies around 0.5 MeV and 0.6 MeV fill the gap between...

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Several correction factors for primary beta dosimetry in radiation protection have been re‑determined by means of measurements and simulations for primary extrapolation ionization chambers. The data are ready for adoption in the international standard series ISO 6980 for beta reference radiation fields.

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Examinations by means of computed tomography (CT) are responsible for about 65 % of artificial radiation exposure in Germany. The aim of personalized CT dosimetry is to individually measure the radiation dose transferred to a particular patient by the radiation field of the CT scanner. High‑precision Monte Carlo (MC) computer simulations are of utmost importance for achieving new developments in...

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In cooperation with the Laboratoire National Henri Becquerel in France, the beta spectrum of samarium‑151 was thoroughly investigated. Measurement data obtained by means of a metallic magnetic calorimeter were used to determine the beta end-point energy with unprecedented accuracy. Furthermore, the researchers involved in this project succeeded in determining the decay probabilities of two...

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Zirconium‑89 is a radionuclide that can be used for diagnostic applications in medicine. At PTB, activity determinations have now been carried out by means of liquid scintillation counting in order to enable reliable calibrations of zirconium‑89 solutions in the future. In addition, ionization chamber measurements have been used to very accurately determine the half‑life of zirconium‑89.

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